Thermally stable fuel composition

ABSTRACT

Thermally stable middle distillate or jet fuel composition containing in combination a Mannich base (alkyl-phenol-sulfideformaldehyde-alkylene diamine reaction product) polymeric acid and metal deactivator.

United States Patent Bialy et al.

1 51 *Apr. 25, 1972 [54] THERMALLY STABLE FUEL COMPOSITION [72]Inventors: Jerzy J. Bialy, Lagrangeville; George W.

Eckert, Wappingers Falls, both of NY.

[7 3] Assignee: Teitaco Inc., New York, NY.

[- Notice: The portion of the term of this patent subsequent to Dec. 17,1985, has been disclaimed.

[22] Filed: Apr. 3, 1968 21 Appl. No.1 718,345

U.S. Cl. ..44/66, 44/73 ...Cl0l 1/18, ClOl l/22 Field of Search ..44/66,73

Primary ExaminerDaniel E. Wyman Assistant Examiner-W. J. ShineAttorney-K. E. Kavanagh and Thomas H. Whaley [57] ABSTRACT Thermallystable middle distillate or jet fuel composition containing incombination a Mannich base (alkyl-phenol-sulfideformaldehyde-alkylenediamine reaction product) polymeric acid and metal deactivator.

6 Claims, No Drawings THERMALLY STABLE FUEL COMPOSITION This inventionrelates to a mineral oil composition and, more particularly, to apetroleum hydrocarbon middle distillate or jet fuel composition havingimproved thermal stability. This invention is an improvement over acommonly assigned application Ser. No. 693,141 filed on Dec. 26, 1967now U.S.

Pat. No. 3,416,903.

It is recognized that petroleum hydrocarbon middle distillates and jetfuels are susceptible to thermal degradation and oxidation resulting inthe formation of a suspension of finely divided insoluble bodies in thefuel and the formation of deposits. The degree that these undesirablechanges take place is dependent on the amount of the unstableconstituents present in the oil and on the temperature stress andoxidation conditions to which the oil is subjected. The thermalstability ratings of the fuel compositions are determined in a FuelCoker Test more fully described hereinbelow.

The problem of thermal stability is particularly serious for hydrocarbonoils which must be maintained at a relatively high temperature forextended periods of time in intimate contact with an oxygen-containingatmosphere. Light middle distillates and jet fuels are maintained insuch an environment in the wing tanks of supersonic aircraft. Thisproblem becomes more acute for jet fuel compositions designed to fuelaircraft having speeds in the Mach 2 and 3 speed ranges or above, suchas the forthcoming supersonic transports, because of the substantiallyhigher skin and wing tank temperatures generated. I v

When a middle distillate or jet fuel has insufficient thermal stability,degradation will take place resulting in the formation of a suspensionof finely divided insoluble bodies. These insoluble bodies are separatedfrom the fuel in the fuel filters of the engine. With excessive amountsof insoluble bodies in the fuel, fuel line filters can become partiallyor completely blocked resulting in seriously curtailed or lost enginepower due to fuel starvation.

' The tendency toward deposit formation in a thermally unstable fuelcauses a deposit build-up referred to as heater tube deposits. Thisdeposit formation simulates the deposit formation on the fuel-oil heatexchanger in a plane where the buildup of deposits will cut down on heatexchanging efficiency thus resulting in lubricating oil overheat andengine failure. In supersonic aircraft, additional fuel-air heatexchangers are present for cooling the passenger and crew space.

A middle distillate fuel oil composition has now been discovered havingsubstantially improved thermal stability. More particularly, a jet fuelcomposition has been discovered which exhibits improved thermalstability even after extended high temperature stress while underconstant agitation in the presence of air.

In accordance with this invention, there is provided a middle distillatefuel composition of enhanced thermal stability containing a minor amountof an additive combination of a Mannich base defined below, a polymericacid and a metal deactivator. More particularly, a middle distillatefuel or jet fuel composition is provided containing from about 0.001 to0.1 weight percent of a Mannich base reaction product formed from analkylphenol sulfide, formaldehyde and an alkylene diamine, from about0.001 to 0.05 weightpercent of a polymeric acid and from about 0.003 to0.005 weight percent of a metal deactivator. Still more particularly,the Mannich base reaction product comprises an alkylphenol sulfide,defined below, formaldehyde and an alkylene diamine, defined below,reacted in mole ratios of a:b:l respectively where a and h each can havea value of from 1 to 8 but a is never greater than b or greater than 4.

The alkylphenol sulfide component of the Mannich base reaction productis represented by the formula:

in which R is an alkyl radical having from four to 60 carbon atoms and zis 1 or 0. The preferred alkylphenol sulfides are those in-which R is analkyl radical having from 10 to 18 car-' bon atoms and z has a valueof 1. When 2 is 0, the alkylphenol sulfide contains 2 moles of analkylphenol and 1 mole of sulfur (2:1) and when r. is 1 the alkylphenolsulfide contains three moles of an alkylphenol and 2 moles of sulfur(3:2). Al kylphenol sulfides are prepared by reacting suitableproportions of an alkylphenol with sulfur dichloride. These materialsare reacted in a solvent, such as isooctane, at a moderate temperaturegenerally from about 15 to 25 C. The reaction mixture is heated toreflux temperature to effect solvent removal and recovery of thealkylphenol sulfide.

The alkylene diamine component of the reactionproduct is represented bythe formula:

in which has a value of 0 to 4. The preferred alkylene diamine for thereaction product is ethylenediamine.

The alkylphenol sulfide, formaldehyde and alkylene diamine components ofthe reaction product are reacted in mole ratios of a:b:1 respectivelywhere a and 12 each can have a value from 1 to 8 but a is never greaterthan b or greater than 4. In general, preparation of the reactionproduct involves mixing the alkylphenol sulfide with alkylene diamineand then adding the formaldehyde solution. The reactants are heated withstirring to a temperature of about C. (176 F.) to effect the reaction.Water is then stripped out of the reaction mixture and the temperatureraised to about 143 C. (290 F.) to insure completion of the reaction.Upon completion of the reaction, a hydrocarbon oil is added to thereaction mixture to make an oil blend of the reaction product. Thisblend is filtered to remove any insoluble materials.

In general, the Mannich base component is employed in the jet fuelcomposition in a concentration ranging from about 0.001 to 0.1 weightpercent. A preferred concentration of the Mannich base is an amount fromabout 0.002 to 0.01 which corresponds to about 5 and 25 PTB (pounds ofadditive material per thousand barrels of fuel) respectively. It isconvenient to employ the Mannich base in an oil blend in which caseallowance must be made for that portion of the additive representing theinert oil carrier.

The polymer acid component of the additive of the invention comprises adimer or trimer of a dienoic or trienoic acid containing from about 16to 18 carbon atoms. Specific olefinic acids which can be employed arelinoleic, linolenic, 9,1l-octadecadienoic and eleostearic acids.Effective polymeric acids can be prepared from naturally occurringmaterials, such as linseed fatty acids, soya bean fatty acids and othernatural unsaturated fatty acids. The preparation of polymeric acids isdisclosed in U.S. Pat. No. 2,632,659. Suitable polymeric acids areavailable commercially, such as Empol 1022 Dimer Acid, a dimer oflinoleic acid.

The polymeric acid is employed in the jet fuel composition in aconcentration ranging from about 0.001 to 0.05 weight percent. Preferredconcentrations are from about 0.0015 to 0.006 weight percent whichcorrespond to about 4 and 16 PTB.

The metal deactivator component of this invention is an aldehyde-aminecondensation product represented by the formula:

(IJH OH in which R is a divalent hydrocarbyl radical having from 2 to 4carbon atoms. Examples of typical deactivator are N,N'-disalicylidene-l,2-propanediamine and N,N-disa1icylidenel ,2- ethane diamine. The metaldeactivator is employed in the fuel at a concentration ranging fromabout 0.0003 to 0.005 weight percent which corresponds to about 0.8 and14 PTB respectively.

The following examples illustrate the preparation of the additiveMannich base component of the invention.

EXAMPLE 1 618 grams (6.0 moles) of sulfur dichloride was added to amixture of 3,660 grams 12.0 moles) of tetrapropenyl phenol and about2,000 ml. of isooctane while the mixture was maintained at a temperatureranging from to 25 C. The reaction mixture was maintained in thistemperature range for about 60 minutes after which the solution washeated to reflux and the isooctane distilled off to effect recovery ofthe tetrapropenyl phenol sulfide.

40.5 grams (0.50 moles) of 37 (w) 7c aqueous formaldehyde was added to amixture of 16.5 grams (0.25 moles) of 85 (w) aqueous ethylenediamine and321 grams (0.50 moles) of tetrapropenyl phenol sulfide. The mixture wasthen heated to 80 C. (175 F.) and stirred there for 6 hours. The waterwas then stripped off and the temperature of the reaction mixture raisedto about 143 C. (290 F.) to complete the formation of the reactionproduct. The reaction product was taken up in approximately 343 grams ofoil to form about a 50 percent by weight blend of thetetrapropenylphenol sulfideformaldehyde-ethylene diamine reactionproduct in oil. The reaction product (active material) of this examplewas called Additive A."

EXAMPLE 2 3,660 grams (12.0 moles) of tetrapropenyl phenol and 824 grams(8.0 moles) of sulfur dichloride were reacted in isooctane as in Example1 to form a tetrapropenylphenol sulfide in the mole proportions of 3moles of alkylphenol and 2 moles sulfur.

328 grams (0.34 moles) of the above tetrapropenylphenol sulfide, 55grams (0.68 moles) 37 (w) 7c aqueous formaldehyde and 22.4 grams (0.34moles) 85 (w) 7c aqueous ethylenediamine were reacted as in Example 1.Approximately equal weight amount of oil was added to the reactionproduct to form approximately a 50 percent by weight blend of the activematerial in the oil solution. The reaction product (active material)ofthis Example was called Additive B.

The preparation of the jet fuel composition of the invention simplyinvolves the addition of the three component additive to the fuel in theindicated quantities. in general, the thermal stability additive will beeffective in middle distillates and jet fuels boiling in the range fromabout 300 to 600 F.

The effectiveness of the additive combination of the invention isdetermined by preparing a typical jet fuel with the additive combinationand testing for thermal stability in a Fuel Coker Test. The Fuel CokerTest employed to test the thermal stability of the fuels of thisinvention was much more severe than the conventional CFR Fuel Coker Test(ASTM-D-l660- 61-T). The reason for a more severe test is that the fuelsnow being formulated for use in supersonic flight are so thermallystable that the conditions of the standard CFR Fuel Coker Test do notapproach or test the thermal stability limits of these fuels. Because ofthis, a much more severe test has been developed called the CFR ResearchFuel Coker Test. This test is patterned after the standard CFR FuelCoker Test and uses similar equipment manufactured by Erdco EngineeringCorporation who make all of the industry adopted Fuel Coker Testequipment. The principal difference in the Research Fuel Coker Test isthat the fuel is maintained at an elevated temperature, usually 200 F.for an extended period of time generally 5 hours all the while beingagitated or stirred in the presence of air. This treatment markedlyincreases the thermal stress placed on the fuel composition. The balanceofthe test is similar to the standard CFR Fuel Coker Test in that thefuel is passed over a heated tube for the determination of tube deposits(tube rating) and through a heated filter to measure filter plugging.The Research Fuel Coker Test is described in Technical DocumentaryReport No. ASD-TDR-62-852, Sept. 1962 of the US. Air Force under thesubject An Investigation of the Thermal Stability of PotentialSupersonic Jet Fuels.

The conditions under which the coking test is conducted follow theprocedure set forth in the CFR Fuel Coke Test wherein the severity ofthe temperature of the heater tube and fuel filter are increased in 25F. increments until the fuel fails to pass the test. These temperaturesare important indicators of the severity of the test and are shown inthe test results. The fuel flow was at a rate of 6 lbs. per hour for 5hours (300 minutes). If the back pressure caused by filter pluggingreaches 25.0 inches of mercury before the 300 minutes, the fuel failsthis test but the run is continued with the filter bypassed until the300 minutes elapse. For military purposes, a filter pressure of lessthan 12.0 inches of mercury in 300 minutes is satisfactory (seeMlL-J-5624F). The deposits formed on the tube are rated as from 0 to 8(where 0 best; 8 worst) depending on the extent of the deposit formationon the tube. A tube rating of 2 or less is satisfactory and a ratinggreater than 2 fails.

The base fuel employed in these tests was a typical jet fuel having thefollowing properties:

Gravity, APl 43.5

Sulfur, 7: 0.02

ASTM Distillation, F.

lBP 327 a 10 361 20 374 30 389 40 404 50 419 435 450 467 487 502 EP 5 l7 The effectiveness of the additives of the invention in the above jetfuel is shown by the CFR Research Fuel Coker Test results set forth inTable 1 below:

TABLE I.RESEARCII COKER TEST Coneen- Pressure tration, Maximum drop Runlbs/1,000 Temperature prehcnter inches, 'litne/ N0. Additive in jet fuellibls. conditions rating 111.: min.

1 Base fuel (no additive) 20O /375 /475 l '2 3. t 300 Base fuel (noadditive) A 200/400/500 1 4 10 300 Commercial thermal stabilityadditive" 30 200/425/525 2 3 0 300 4N,Ndisalicylidene-1,Z-propanediaminc... 1. 5 200/425/5% 2 3 l5 1 2515 5Additive B 8 200/425/525 2 3 0. 2 300 5a Dimer acid... 0 .200/425/525 16 l5 1 180 1 g 200/425/525 1 3 0.1 300 6 "{N,N -disalieylidcne- 1. 5ZOO/W550 2 3 s 2 200/4 5/5 1 3 t 300 Additive B S 0 Dimer acid 6200/450/550 l .2 0 300 N,N-disalieylidene-1,2-propanediamine. 1. 5

1 Pass. V 2 Fail.

Temperature of prcheater. 0 Temperature of filter.

Dimer acid, dimer of linoleic acid, Empol 1022.

It is evident from the above results that a jet fuel composition ofoutstanding thermal stability has been provided by the invention asexemplified in Run 9 above. This improvement greatly extends the abilityofajet fuel composition to meet the stringent heat stress requirementsof fuels for advanced turbine powered aircraft. 1

Obviously, many modifications and variations of the invention, ashereinabove set forth, may be made without departing from the spirit andscope thereof, and therefore, only such limitations should be imposed asare indicated in the appended claims.

WE CLAIM:

l. A middle distillate fuel composition consisting of petroleumhydrocarbons boiling in the range from about 300 to 600 F. containing incombination from about 0.001 to 0.l weight percent of the reactionproduct of an alkylphenol sulfide, formaldehyde and an alkylene diaminein mole proportions of a:b:l respectively, where a and b each can have avalue from 1 to 8 but a is never greater than b or greater than 4, saidalkylphenol sulfide having the formula in which R is an alkyl radicalhaving from 4 to 60 carbon atoms and z is l or 0, and said alkylenediamine has the formula of an aldehyde-amine condensation productrepresented by the formula in which R is a divalent hydrocarbyl radicalhaving from two to four carbon atoms.

2. A middle distillate fuel composition according to claim 1 in whichthe alkyl radical R in said alkylphenol sulfide has from 10 to 18 carbonatoms.

3. A middle distillate fuel composition according to claim 1 in whichsaid alkylphenol sulfide is tetrapropenylphenolsulfide (3:2 mole ratio)and said alkylene diamine is ethylenediamine.

4. A middle distillate fuel composition according to claim 1 in which aand b each have the value of 2.

5. A middle distillate fuel composition according to claim 1 in whichsaid polymeric acid is the dimer of linoleic acid.

6. A middle distillate fuel composition according to claim 1 in whichsaid aldehyde-amine condensation product is disalicylidene-l ,2-propanediamine UNITED STATES, PATENT OFFICE A CERTIFICATE OF CORRECTION 1Patent No. 3 8 496 Dated April 25 1972 Inventor(s) JeIZY J Bialy, 'et a1It is certified that error eppears in the above-identified patent 'andthat said Letters Patent are hereby corrected as shown below:

. Column 1, line 61', "0.003" should read 0.0003 Column 2, line 54, "'U.8. 2,632,659" should read U.-S. 2,632,695

Signed and sealed this 2nd day of January 1973.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents FORM PC4050 USCOMM-DC 60376-P6D R U.S. GOVERNMENT PRINYINGOFFICE: IBIS 0-356-334,

2. A middle distillate fuel composition according to claim 1 in whichthe alkyl radical R in said alkylphenol sulfide has from 10 to 18 carbonatoms.
 3. A middle distillate fuel composition according to claim 1 inwhich said alkylphenol sulfide is tetrapropenylphenol sulfide (3: 2 moleratio) and said alkylene diamine is ethylenediamine.
 4. A middledistillate fuel composition according to claim 1 in which a and b eachhave the value of
 2. 5. A middle distillate fuel composition accordingto claim 1 in which said polymeric acid is the dimer of linoleic acid.6. A middle distillate fuel composition according to claim 1 in whichsaid aldehyde-amine condensation product isN,N''-disalicylidene-1,2-propane diamine